Thanks for taking interest in GroupDocs.Viewer for Java 3.x and posting your concerns.

Can you please answer following questions so that we can provide you convenient answer against your hardware requirement needs:

Which document types you are going to render with GroupDocs.Viewer for Java 3.x?

Which rendering engine you are intended to use (Image or Html)?

Will you use GroupDocs.Viewer caching?

How many expected users will be interacting with the application and is there any possibility that all of them will work/interact with system at the same time?

Please note that when GroupDocs.Viewer cache is enabled (ViewerConfig.UseCache = true), the first time when you render document it consumes more resources and time than when you render document for the second time. Actually when you render document second time then GroupDocs.Viewer extracts data from the cache.

Though you are viewing Word and Pdf docs most of the time, document rendering performance may vary from one document to other depending on the content of documents. A document may contain images/tables/graphics/formatting styles or other clip-arts. Hence, we can not provide you any estimated value as it varies all the time for different documents in different environments.

Please note, when GroupDocs.Viewer cache is enabled (ViewerConfig.UseCache = true) the first time when you render document it consumes more resources and time than when you render document from the second time then GroupDocs.Viewer extracts data from the cache and consumes less time and resources.

We got a response from the product team. There are multiple factors involved in document rendering like document size or content. However, minimal system requirements to run GroupDocs.Viewer for Java is JDK 1.6. So, if you have machine with JDK 1.6, you can run viewer on it.

We’d also suggest you to test your application with multiple users on a small scale and monitor the consumption of the RAM. This will also give you an idea that how much RAM the application is using for a specific number of the users.